Low-impact development facilities for stormwater runoff treatment: Field monitoring and assessment in Xi’an area, China

[Display omitted] •Field performance data were obtained for four typical LID facilities.•Exceedance probabilities of effluent concentration is reduced obviously.•The weighted annual load reduction is more than 60% and stable.•An estimation method for LID extent and cost in urban built-up areas is proposed. Field studies are valuable because of the insufficient number of field performance data in low-impact development (LID)-related research. Four typical LID facilities in northwest China were built and monitored. These facilities differ in their impervious/pervious bottom, inflow underlying surface, media types, and combinations. The water volume reduction of impervious rain garden filled with native loess decreases by approximately 20% when the total daily rainfall levels gradually increase from light to heavy. Several technical measures, such as media modification, setting internal storage area, reducing drainage area, and increasing media thickness, have been taken to improve the runoff regulation effect. The volume reduction rate in light and medium-sized rainfall (daily rainfall totals